Despite claims that the modern approach to interpretation of contracts has usurped much of its function, the equitable jurisdiction to rectify a written contract on the ground of common mistake remains one of the most practically important areas of the law of contract. Rectification claims are a regular feature of modern commercial litigation, very often of course in tandem with interpretation disputes. And, as Lord Neuberger of Abbotsbury M.R. pointed out in Daventry District Council v Daventry & District Housing Ltd, since "rectification most commonly arises in a commercial context, it is plainly right that the applicable principles should be as clear and predictable in their application as possible". Unfortunately, recent case law demonstrates that in fact the principles are not as clear and predictable in their application as they should be......The purpose of this article is to suggest a way out of the current uncertainty and complexity. The law of rectification really ought to be quite straightforward but it has become needlessly difficult, largely as a result of a misunderstanding of the principles of contract formation, particularly those concerning the meaning of the objective test and the relevance of the parties’ actual or subjective intentions. Properly understood, those principles dictate that the remedy of rectification ought ordinarily to be available to a claimant who is mistaken as to the terms expressed in a written contract where it is convincingly proven either (a) that the other party made the same mistake, or (b) that, despite what the document on its proper construction provides, the claimant was led reasonably to believe that its understanding of the terms of the contract had been accepted by the other party. In other words, the failure of the document to reflect either the actual or objective intention of the parties should suffice for rectification.